I shoot a lot of BP and believe 4f is to fine for loading 45/70 or a cap and ball revolver.  Should use Swiss 1 1/2f or Goex 2f in the 45/70 and 3f in the revolver.  4f is normally used in the flash pan of flintlocks.  BP also needs to be packed tightly in the case or cylinder behind the bullet, no air gap.